* Fix various issues detected by megacheck
I've ran honnef.co/go/tools/cmd/megacheck and fixed a few of the
things that came up there.
* Cleanup using Gogland
According to https://golang.org/cmd/go/#hdr-Test_packages
service_test is more appropriate becuase this directory contains
no non-test code and the intention is to compile these *_test.go
files as a separate package and link/run with the main test package.
* service/api: Removed unused fields of service/api.Function
* proc/eval: Set return variable name to input expression
* all: fine-grained control of loadValue for better variable printing
Makes proc.(*Variable).loadValue loading parameters configurable
through one extra argument of type LoadConfig.
This interface is also exposed through the API so clients can control
how much of a variable delve should read.
New API version with better backwards compatibility plus mechanism to
select the API version that a headless instance should use.
Adds service/test/cmd/typecheckrpc.go to type check the RPC interface.
